Intermittent fasting alleviates the neuropathic phenotype in a mouse model of Charcot–Marie–Tooth disease
ABSTRACT Charcot–Marie–Tooth type 1A (CMT1A) neuropathies linked to the misexpression of peripheral myelin protein 22 (PMP22) are progressive demyelinating disorders of the peripheral nervous system. In this study we asked whether dietary restriction by intermittent fasting (IF) could alleviate the neuropathic phenotype in the Trembler J (TrJ) mouse model of CMT1A. Our results show that neuropathic mice kept on a five month long IF regimen had improved locomotor performance compared to ad libitum (AL) fed littermates. The functional benefits of this dietary intervention are associated with an increased expression of myelin proteins combined with a thicker myelin sheath, less redundant basal lamina, and a reduction in aberrant Schwann cell proliferation. These morphological improvements are accompanied by a decrease in PMP22 protein aggregates, and enhanced expression of cytosolic chaperones and constituents of the autophagy–lysosomal pathway. These results indicate that dietary restriction is beneficial for peripheral nerve function in TrJ neuropathic mice, as it promotes the maintenance of locomotor performance.
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ABSTRACT: Charcot-Marie-Tooth disease type 1A (CMT1A) is a hereditary demyelinating neuropathy linked with duplication of the peripheral myelin protein 22 (PMP22) gene. Transgenic C22 mice, a model of CMT1A, display many features of the human disease, including slowed nerve conduction velocity and demyelination of peripheral nerves. How overproduction of PMP22 leads to compromised myelin and axon pathology is not fully understood, but likely involves subcellular alterations in protein homeostatic mechanisms within affected Schwann cells. The subcellular response to abnormally localized PMP22 includes the recruitment of the ubiquitin-proteasome system (UPS), autophagosomes and heat shock proteins. Here we assessed biochemical markers of these protein homeostatic pathways in nerves from PMP22-overexpressing neuropathic mice between the ages of 2-12 months to ascertain their potential contribution to disease progression. In nerves of 3 week old mice, using endoglycosidases and western blotting, we found altered processing of the exogenous human PMP22, an abnormality that becomes more prevalent with age. Along with the ongoing accrual of misfolded PMP22, the activity of the proteasome becomes compromised and proteins required for autophagy induction and lysosome biogenesis are upregulated. Moreover, cytosolic chaperones are consistently elevated in nerves from neuropathic mice, with the most prominent change in HSP70. The gradual alterations in protein homeostatic response are accompanied by Schwann cell de-differentiation and macrophage infiltration. Together, these results show that while subcellular protein quality control mechanisms respond appropriately to the presence of the overproduced PMP22, with aging they are unable to prevent the accrual of misfolded proteins.ASN Neuro 10/2013; DOI:10.1042/AN20130024 · 4.44 Impact Factor
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ABSTRACT: Charcot-Marie-Tooth type 1A (CMT1A) is the most common inherited neuropathy. The phenotype of patients affected by CMT1A is highly variable and may be influenced by several conditions. We evaluated how comorbidities such as diabetes, hypothyroidism, exposure to toxins and obesity can modify or exacerbate the clinical and neurophysiological phenotype of CMT1A patients. Disability was measured using the classic CMT neuropathy score. Compared to controls, all groups of CMT1A patients with comorbidities had higher CMT neuropathy score. In particular, patients with CMT1A and diabetes mellitus show motor subscores which are significantly higher than in control CMT1A. Amplitudes of ulnar CMAP are lower in patients with CMT1A and diabetes mellitus, but not at a significant level. As expected, motor nerve conduction velocity is not influenced by any of the comorbidities. The presence of concomitant diseases shows a tendency to worsen the clinical and neurophysiological CMT1A phenotype, especially in patients with CMT1A and diabetes mellitus, where higher values in the CMT neuropathy score and clinical motor subscore have been observed.Neuromuscular Disorders 07/2013; 23(11). DOI:10.1016/j.nmd.2013.07.002 · 3.13 Impact Factor
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ABSTRACT: Autophagy is emerging as a central regulator of cellular health and disease and, in the central nervous system (CNS), this homeostatic process appears to influence synaptic growth and plasticity. Herein, we review the evidence that dysregulation of autophagy may contribute to several neurodegenerative diseases of the CNS. Up-regulation of autophagy may prevent, delay or ameliorate at least some of these disorders, and - based on recent findings from our laboratory - we speculate that this goal may be achieved using a safe, simple and inexpensive approach.European Journal of Neuroscience 01/2011; 33(2):197-204. DOI:10.1111/j.1460-9568.2010.07500.x · 3.67 Impact Factor